Is my TiBook 550 underclocked?

[Peter King]

I've heard a lot about certain Macs being "underclocked" by Apple, and many people have said that a TiBook 550 can be overclocked to 667 MHz pretty easily. Anyone know if this is true? Also, my 550 only has a 100 MHz bus, and I'd like to overclock that to 133. Is this possible?

 

[ksv]

Originally posted by Peter King
I've heard a lot about certain Macs being "underclocked" by Apple, and many people have said that a TiBook 550 can be overclocked to 667 MHz pretty easily. Anyone know if this is true? Also, my 550 only has a 100 MHz bus, and I'd like to overclock that to 133. Is this possible?

It's possible, but not very safe. And really challenging. The only way to see if your processor is underclocked is to remove the heatsink and see what the processor says. But, Apple probably had a reason to underclock it if it is, so it would probably be unstable at 667 MHz. Some work, though. It has a better chance to work if it doesn't run very hot.
I tried to overclock the bus on my PB 550 to 133 MHz, but it failed to boot, so I clocked it back down to 100 MHz. If you try this, make sure you have PC133 RAM.
Here are the PLL settings for 667/133 MHz on the Gigabit Ethernet logic boards:
http://village.infoweb.ne.jp/~fwid8843/PBG4_BASE/PB550_base.html